Automatic lapping machine



Dec, 9, 1930. H. J. wlLLs 1,784,648

AUTOMATIC LAPPING MACHINE Filed Dec. 26, 192B III llllllllllll INVENTOR Havbv J'. Ulls ATTORNEY Patented Dec. 9, 1930 UNITED.. STATE-s' PATENr OFFICE HERBERT .J1 wILLs, or maenner-Ams, NEW YORK, Assreivon To THE CARBO- RUNDUM vcoinrmw AUTOMATIC Laer-ING MACHINE 'Application led December 26.1928. serial No. 328,556.

My invention relates to -an improvement in automaticllapping machines, in which articles to be' polished are to be dropped into themachine which rolls them around in contact with abrasive material and against moving or stationary parts in a manner to give the article the suitable amount of lapping or. abrasive action before it is discharged into a hopper.

lThe Object of my invention is to' pi'ovidea ma- 1o chine which is of avery simple character and which is also automatic in its action by reason of the angular relation'of an ad]ust able stationary part with respect to certain rotatable (or floating) and stationary parts.

Lapping machines ordinarily have an upper lapping plate and a lowerl lapping plate mounted on parallel or coincident ver? tical axes'. Between the upper and lower plates is mounted a worleholder which is usually mounted to carry the parts to .be

lapped in complicated (and where possible non-repeating) paths to prevent the grinding becoming localized with a resulting uneven working on the article. These work-holders have in general to be provided withv carefully shaped matrices which have to be filled by hand with the articles to be ground or-lapped, and which, due to the abrasion, wear rapidly requiring frequent renewals. Frequently parts to be lapped stick in these matrices with resultant flat spots. In some cases stop mechanism is provided which prevents the approach of the lapping plates toward each other too closely and so limits theV grinding done on the articles. In many cases however it is unnecessary to grind the article eXtensively. Centerless grinding machines for eX- ample turn out cylindrical bodies such as piston pins which are uniform within a few ten thousandths of an inch. Such'cylindrical articles often require therefore only a small l amount of lapping. It is the -object of my Bussum Figure 1 is a vertical section showing u per and lower operating plates andlapping ars intermediate the operating plates;

Figure 2 represents a plan view (seen from above), the right half of the upper operating plate having'bcen removed;

Figure 3 represents a plan view of the lapping bar;

Figure t is an elevation showing the support for the lapping bar;

Figure 5 isaJ section on the line 5 5 of Fig. 3; and

Figure 6 is an edge view of the lapping surface 36 showing grooves along which abrasive material distributes itself.

In Figure 1 a frame 2 carries a lower operating plate 3vwhich is supported on bearings/4f located about midway between the inner and outer radial edges of the lower operating plate. The lower lapping plate 1s rotated by means of a drivingv shaft 5p from which -the drive is through a bevel driving gear 6, a driven bevel gear 7, 'a

shaft 8, a spur pinion 9 and a spur driven gear 10, which driven gear is secured to the lower side of the table 3. An upper plate 12 is mounted concentrically with the lower plate 3 on the upper 'end of an extended shaft 13. This shaft is separated from a cylindrical portion 14 of the frame 2 by means of radial bearings 15; The weight of the upper plate is carried partly by the parts to be lapped and partly by the shaft 13 which is supported on a step bearing 16. The low-` er end of the .shaft 13 is threaded to engage with a nut 17 having bevelled teeth which are engaged by a bevel pinion 19 mounted on a shaft 20. The lower end of the shaft 13 is slidably engaged with the frame at 21. With the mechanism just described the plate 12 may be raised or lowered by turning the V shaft 20. v

A series of lapping bars 30 are adjustably v mounted on the frame 2 in a position to project between the lower and upper opcrating plates. These bars 30 may be fixed at any desired position to `which they have been rotated by tightening the bolt 3], by means of a wrench applied to the head 32. The lapping surface of the lapping. bar 30 is indicated at 36. This surface as shown inig. 5 has a vertical section which is the arc of a circle. Most of the lapping is done on this circular surface. In Figure 5 a cylindrical article (to be lapped) is indicated as in Contact with a lapping bar 30.

Abrasive grains carried by suitable vehicles (lubricants etc.) aresupplied through a cup 33 from which they are fed through a channel 34 and an opening et() in the working surface of the lapping bar.

An index nia-y be provided on the edge 39 i of the bar support to indicateI various angular positions of the lapping bar SO witlrrespect to a plane passing through 'the axis of rotation of the operating` plates and the axis of rotation of the lapping bar 30. V

The upper operating plate is strengthened by means of radial ribs 37.

ln operating the device which is the subject of my invention piston pins or other cylindrical articles are fed by gravity from a hopper to the outer edge of the lower lapping plate. They are rotated against the lapping bar and carried inward by the lower operating plate until they reach the surface 3G of the lapping bar 30, where they are rolled in contact with the lower operating plate, the lapping bar and the upper operating plate. The vert-ical position of the latter plate may be controlled the operator b v rotation of the shaft 20 as mentioned above. K

lf the rotation of the lower operating plate be in the direction indicated b v the arrow A as shown in Fig. 2, the frictional forces exerted bythe lower plate will tend to Ycarry the articles inward along the, lapping bar until they fall through the interior opening 38, .into a receptacle beneath. By adjusting the lapping bars to different angular positions as mentioned above theI` length-of time that the articles are lapped may be vvaried to suit the amount of lapr ping required.

1iVhile in the descriptionv cylindrical articles such as piston pins have been mentioned particularly as-adapted to be lapped by my machine, articles having fiat surfaces (either round or rectangular) may also be lapped, in which case. both plates are driven in the same direction but at diiierent speeds. By feeding abrasive grains to the outer ends only of the lappingbar. parte may he bo'th lapped andlpolished in one complete operation. The lapping bar may be of cast iron, brass, copper or metal provided with a wooden face to suit many. conditions.

By applying a brake on the upper plate the abrasive action may beconsiderably increased.- The abrasive action may also be controlled bv such factors as the angle of the lapping bar, the speed of the operating plate, the Weight of the top floating plate. the selection ofthe abrasive, the point of mettete .ing plates do not require frequent resurfaclai/ly machines are particularly adapted for mass' production since each machine,` automatically laps a large number of articles in succession and one operator may attend to a number of machines.

1. An automatic lapping machine forap-l lproximately cylindrical parts 'comprising in combination a lower `operating plate with plane upper surface and having a central outlet opening, an upper iioatingjplate with plane lower surface, a lapping bar held in a predetermined position between said lower and upper plates, said lapping bar having a grooved grinding surface Whose generating lines are parallel to said plane surfaces of said plates and are inclined to the adjacent radii of said plates, means for rotating saidV lower plate to revolve approximately cylinasv drical objects to be lapped against the grinding surface of said lapping bar as well as iagainst the upper plate, the rotation of the lowerv plate being in such a direction that the frictional forces exerted by the lower plate on the objects to 'be lapped have components toward the central opening of the lower plate, means for adjusting the height of said upper plate above said lower plate, and means for adjusting the angular position of said lapping bar in a plane parallel to the plane surfaces of the plates which contact with the cylinders, whereby the time of travel of the cylindrical parts from the circumference of the lowerl plate to the central opening thereof may be varied.

2. An automatic lapping machine comprising in combination' an operating plate havinoa plane upper surface and having a centra outlet opening, a lapping bar held in a. prede! termined position above said operating plate, said lapping bar having a grooved grinding surface Whose generating lines are parallel tov the upper surface of said operating plate, and

` means for rotating said operating plate to revolve approximately cylindrical objects to be lapped against the grinding surface of said lapping bar, the rotation of the operating plate being in such a direction that the fric@ tional forces exerted by the operating plate on the objects to be lapped have components toward the central opening of the operating l plate, and means for adjusting the angular position of said lapping bar in a plane parallelto the upper surface of the operating plate whereby theduration of the lapping of the articles to be lapped may be varied at the Will of the operator.

3. rihe lapping machine described in claim l in which the lapping bar contains means for feeding abrasive grains and necessary lubricant at the lapping surface of the lapping bar., i

. 4. 'llie lapping machine described in claim 2 in which the lapping bar contains means for feeding abrasive grains and necessary lubri- R gant at the lapping surface ci' the lapping 5. The lapping machine described in claim 3l in which the intensity of the lapping action is varied by the application of a brake to the upper plate. l 4

in testimony whereof ll ax my signature HEBERT J. WILLS. 

